Generally, in a record/play selection of a digital audio tape recorder, there are six operational modes including four-channel, long play and the like. An analog audio signal received in either a four-channel operational mode or in long play operational mode is used for a digital in which a sampling frequency is 32 KHz, a quantization is 12 bits, and information quality of each channel is 768K bit/sec (2.times.32 KHz.times.12 bits=768K bit/sec). A long play mode is provided for recording data for relatively long periods. Standard data is provided with a sampling frequency of 48 KHz, a quantization is 16 bits, and information quantity for each channel equals 768K bit/sec (48 KHz.times. 16 bits=768K bit/sec). Accordingly, to achieve long recording in a digital audio tape recorder, a data compression circuit is required for compressing standard data into compressed digital data.
A data compression circuit for converting 16-bit standard data to 12-bit compressed data is disclosed in Korean Patent Application NO. 89-20148. Conventional data compression circuits are inaccurate in compressing 16-bit standard data to 12-bit compressed data. Thus, the present invention provides an improved data compression circuit, resulting in more accurate compression of data.